Off-line CAM cuts programming times in half

By switching to EdgeCAM computer-aided machining software, Crabtree of Gateshead has not only reduced programming times by up to 50 per cent, it has saved time and expense.

By switching to EdgeCAM computer-aided machining software, Crabtree of Gateshead has not only reduced programming times by up to 50 per cent, it has saved time and expense normally associated with the production of additional post-processors for different machine tools on its shopfloor.

The installation of EdgeCAM, by Pathtrace of Reading, has also given the established North East company unparalleled levels of programming flexibility compared with its previous system and since on-screen program prove-out is now immediately available, the likelihood of mistakes are minimised.

Another major benefit of the new software, according to senior production engineer, Paul Robson, is the fact that the system doesn't demand that users are skilled typists! "Because everything is based on mouse-moves, not only is program creation faster but it is also user-friendly." As part of the GBP 31 million turnover LTG Technologies group, Crabtree is a global player in the metal-decorating machinery and equipment market.

For the past 40 years or so it has been designing and manufacturing a range of printing presses, coaters and drying ovens that are supplied to customers throughout the world who are involved with, for example, petrol can and biscuit tin manufacture.

While the company's roots can be tracked back to the 1800s and it has, since the '50s occupied its current site in Gateshead that during the 1939-45 war was the base for the British army's Bren gun manufacture.

However, there is nothing old-fashioned about the 250-employee company that today adopts a series of modern manufacturing practices to maintain its long-standing reputation.

For instance, its team of designers is continually using the latest CAD system to update and improve product design and function, while on the shopfloor, there's a large battery of CNC production equipment to enable the company to produce most of its own machined components.

All fabrication and sheet metalwork, as well as specialised tasks like gearcutting are outsourced and it is this combination of in-house and sub-contract manufacture that enables the company to produce a complete turnkey printing line.

These can involve sheet in-feed systems at one end and drying ovens at the other and can be built within a 12 week average lead time.

A varied range of spare parts is also produced.

"EdgeCAM plays a key role in enabling us to achieve such short lead times," maintains Paul Robson.

"However, that wasn't the case before EdgeCAM was installed.

Taking designs that are created primarily in SDRC, we found that our former CAM programming procedures placed too many restrictions on us," he continues.

Crabtree produce a host of small batches.

Paul Robson explains: "Sixteen is considered a large batch and with such a wide range of different machine tools, and therefore different control systems, means that every time we change or process a certain part on a different CNC machine, we had to pay for a new post-processor to be written." However, with EdgeCAM's Code Wizard, Crabtree engineers are able to complete a simple template that, through easy to tweak stages enables them to quickly generate their own post-processor.

"This not only saves us a lot of time, money and hassle but, equally important, it also gives us so much more freedom and flexibility in production planning and more importantly, rescheduling our workloads." Explaining that Crabtree's four-seat EdgeCAM installation is used mainly for straightforward two- and 2.1/2 axis turning and milling applications, Paul Robson adds that the programmers often find it quicker to 'redraw' these components within EdgeCAM rather than working with the imported SDRC design data which is mainly used for more complex multi-axis work.

He describes a classic example of the savings being made through EdgeCAM's powerful functionality in the programming of a series of holes used in the production of large press frames.

The frame periphery contains a large number of holes and, in the past, it was sometimes difficult to see exactly what was happening when programming a series of particular diameters.

Now, with EdgeCAM certain holes can be switched on and off which they feel makes the task a lot less confusing and hence, less likelihood of costly mistakes.

"This means programming is also faster because we are just using the mouse to point and click," he says.

Today, Paul Robson and his team program 75 per cent of components off-line which are DNC-fed to a variety of turning, milling machines and machining centres.

The remaining "very simple" turning work is programmed on the shopfloor by direct input at the machine control.

With a program library of circa 30,000 parts, the transition period between dispensing with the old programming system and fully utilising EdgeCAM was described by Paul Robson, as 'trying!' He explains: "For a while we ran the two systems in parallel - mainly because we initially thought that many of the jobs couldn't be achieved on EdgeCAM.

However, we quickly realised that our new system was so superior that it would be best to concentrate solely on EdgeCAM." He remembers how it literally took years for them to get to know the old system.

"But after just one week's training and an additional day to cover multi-plane work and Y-axis turning we were up and running with EdgeCAM," he says.

One thing that helped the switch was that Crabtree's parts are catalogued with prefixes that relate to a drawing number, set-up data and tooling sheets, for example.

"This is all held on the same database, which made the changeover so much easier," he says.

EdgeCAM offers users like Crabtree a host of valuable time-saving benefits such as the improved control over toolpath, lead-in and lead-out which reduces the possibility of tool and component collision by ensuring the tool is removed cleanly and safely from the working area.

To enable faster identification of an attribute for modification, users can also designate names for the specific layers on a component.

Toolpath regeneration time is also fast because the current programming task is stored in a cache memory.

EdgeCAM selects only those areas of the working parts that have been changed and regenerates the associated toolpath accordingly.

The toolpath does not need to be completely recalculated, therefore this saves time and increasing, improves overall productivity.

Paul Robson and his team are especially pleased with the system's user-friendliness and this is particularly evident within the ToolStore module which is based on two direct side-by-side screen panels.

In addition, tool kit creation is simplified to allow the selection of tools and material combinations for use in future projects.

He explains how they find ToolStore a very useful feature: "Editing used to be a nightmare but now it's so easy, it takes just seconds to use a new tool and the ability to see a three-dimensional model of that tool in action was something we never had before." EdgeCAM also features a Stock Creation Command that enables stock material to be created automatically relative to and with consideration to the boundaries of any component design model.

An override facility enables additional material to be created beyond the boundary if required.

In conclusion, Paul Robson maintains that for Crabtree, EdgeCAM's features add up to a user-friendly system that offers general flexibility and faster programming with less likelihood of mistakes.

"We couldn't ask for anything more," he says.

(This was Manufacturingtalk's Top Story on 4 February 2002).

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